Linux : mount.nfs: Input/output error

Problem:

Red Hat 5

# mount /u00
mount.nfs: Input/output error

Solution :
service portmap start
chkconfig portmap on
chkconfig nfs on
chkconfig netfs on

Linux : mount.nfs: rpc.statd is not running but is required for remote locking

Problem:

# mount -t nfs 10.10.100.20:/vol/test1/NFSDS01 /mnt
mount.nfs: rpc.statd is not running but is required for remote locking.
mount.nfs: Either use '-o nolock' to keep locks local, or start statd.
mount.nfs: an incorrect mount option was specified

But rpc.statd is running
$ ps -ef | grep rpc.statd
rpcuser 2578 1 0 16:18 ? 00:00:00 rpc.statd
rpcuser 4824 1 0 16:21 ? 00:00:00 rpc.statd --no-notify
rpcuser 4867 1 0 16:22 ? 00:00:00 rpc.statd --no-notify
rpcuser 9287 1 0 17:05 ? 00:00:00 rpc.statd --no-notify
rpcuser 10235 1 0 17:15 ? 00:00:00 rpc.statd --no-notify

Solution:

vi /etc/hosts.allow

rpcbind portmap nfsd statd mountd lockd: 127.0.0.1 10.10.100.20 : ALLOW

Oracle VM Manager : OVMRU_002024E Cannot perform operation

Error message : OVMRU_002024E Cannot perform operation


Solution :
As specified in the error message:

File Server: NAS_NFSDS01, has invalid exports. Export: /vol/vol0, is contained in export: /vol/vol0/home. Remove one of those exports on the file server, and then refresh the file server to clear the error

This is described in the release notes - http://docs.oracle.com/cd/E50245_01/E50246/html/vmrns-storage.html#vmrns-refreshing-nas-invalid and the workaround generally is:

"do not export top level file systems in the NAS-based file server's exports file"

The error in this case explicitly tells you that the export /vol/vol0 is contained in the export /vol/vol0/home and you need to remove one of those exports and then refresh the file serv.

Linux : Create a 1G empty file

# dd if=/dev/zero of=1g.img bs=1G count=1
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB) copied, 54.018 s, 19.9 MB/s

# ll 1g.img
-rw-r----- 1 root root 1073741824 Jan 22 14:03 1g.img

# stat 1g.img
  File: `1g.img'
  Size: 1073741824      Blocks: 2105424    IO Block: 65536  regular file
Device: 13h/19d Inode: 97          Links: 1
Access: (0640/-rw-r-----)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2015-01-22 14:03:05.231563000 -0500
Modify: 2015-01-22 14:03:59.115150000 -0500
Change: 2015-01-22 14:03:59.115150000 -0500

Linux : List Ethernet Network Card Hardware and kernel driver information

# lspci | grep -i ether
03:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5719 Gigabit Ethernet PCIe (rev 01)
03:00.1 Ethernet controller: Broadcom Corporation NetXtreme BCM5719 Gigabit Ethernet PCIe (rev 01)
03:00.2 Ethernet controller: Broadcom Corporation NetXtreme BCM5719 Gigabit Ethernet PCIe (rev 01)
03:00.3 Ethernet controller: Broadcom Corporation NetXtreme BCM5719 Gigabit Ethernet PCIe (rev 01)
24:00.0 Ethernet controller: Intel Corporation 82599ES 10-Gigabit SFI/SFP+ Network Connection (rev 01)
24:00.1 Ethernet controller: Intel Corporation 82599ES 10-Gigabit SFI/SFP+ Network Connection (rev 01)

# grep -i "10 Gigabit" /var/log/messages
Nov  2 19:22:00 localhost kernel: ixgbe: Intel(R) 10 Gigabit PCI Express Network Driver - version 3.15.1-k
Nov  2 19:22:00 localhost kernel: ixgbe 0000:24:00.0: Intel(R) 10 Gigabit Network Connection
Nov  2 19:22:00 localhost kernel: ixgbe 0000:24:00.1: Intel(R) 10 Gigabit Network Connection
Nov  3 09:41:46 localhost kernel: ixgbe: Intel(R) 10 Gigabit PCI Express Network Driver - version 3.15.1-k

# lsmod | grep ixgbe
ixgbe                 243936  0
mdio                    4769  1 ixgbe
ptp                     9614  2 ixgbe,tg3
dca                     7101  2 ixgbe,ioatdma

Linux : Boot Kernel to Single User Mode or Emergency Mode

http://www.linuxsv.org/training/l1_linux_boot.html

The way that uses GRUB to load the Linux Kernel can be customized directly at the console typing "e" following the instructions of the GRUB graphical menu showed at startup or directly modifying the file /etc/grub.conf: 

kernel /vmlinuz-2.6.18-53.el5 ro root=/dev/VolGroup01/LogVol00 rhgb quiet s
Single user mode "s" that provides a root shell without root password check. Very useful for root password recovery. 

kernel /vmlinuz-2.6.18-53.el5 ro root=/dev/VolGroup01/LogVol00 rhgb quiet emergency
Emergency mode provides a maintenance root shell after root password check. 

kernel /vmlinuz-2.6.18-53.el5 ro root=/dev/VolGroup01/LogVol00 rhgb quiet init=/bin/sh
With this configuration you can startup the system skipping the init process. It provides a root shell after root password check. 

kernel /vmlinuz-2.6.18-53.el5 ro root=/dev/VolGroup01/LogVol00 rhgb quiet 5
Graphical mode startup, the default behaviour. 

kernel /vmlinuz-2.6.18-53.el5 ro root=/dev/VolGroup01/LogVol00 rhgb quiet selinux=0
SElinux can be disabled at kernel boot time with this configuration.

Linux : NFS : Some NFS file systems are not mounted after reboot

Problem : Some NFS file systems are not mounted after reboot

Solution : Add options to /etc/fstab

Original fstab :

10.11.200.101:/test /test           nfs     rw      0 0

After :
10.11.200.101:/test /test           nfs     rw,bg,hard,rsize=32768,wsize=32768,vers=3      0 0

Also the following services need to be turned on

chkconfig nfs on
chkconfig portmap on
chkconfig netfs on